Edge-adjacent faces are found using the internal face graph connectivity, while the RegionType related class depends on three parameters:

• distance_threshold - the maximum distance from the furthest face vertex to a plane;

• angle_threshold - the maximum accepted angle between the face normal and the normal of a plane;

• min_region_size - the minimum number of mesh faces a region must have.

The first two parameters are used by the functions RegionType::is_part_of_region() and RegionType::update(), while the third parameter is used by the function RegionType::is_valid_region() explained in Section Framework Regions. The right choice of these parameters is as important as the one explained in Section Parameters For Region Growing On Point Set.

before running the program, use the commands below to make Eigen work properly:

cd /usr/local/include

sudo ln -sf eigen3/Eigen Eigen

sudo ln -sf eigen3/unsupported unsupported

This CGAL component implements two algorithms for shape detection:

• the Efficient RANSAC (RANdom SAmple Consensus) method;
• the Region Growing method.

Efficient RANSAC is designed for the unstructured point set with unoriented normals. This algorithm detects a set of shapes. Five types of primitive shapes are provided by this package: plane, sphere, cylinder, cone, and torus. Other primitive shapes can be easily added by the user as well.